MatLab: Understanding the Size Command

[robax25]

I have a little bit confusion that how size command work.can body explain please?. For Example
A=[1 2 3;4 5 6;7 8 9];
size(A)
=3 *3
but size(A,1)=3 and size(A,2)=3 and size(A,3)=1 why is size(A,3)=1?

 

[Wrichik Basu]

When you are doing $size(A, 1)$ or $size(A, 2)$, 1 and 2 are dimensions here, not the row or column. Since the array is 3×3 (a two-dimensional matrix), the 1st dimension is 3, and the second is 3.

If you create a 3×3×3 matrix (a three-dimensional matrix), the 3rd dimension would be 3, but any higher order dimensions would be 1.

As a basic rule, if an array $A$ is n-dimensional, then $size(A, dim)$ returns the size of that dimension. If $dim$ exceeds $n$, then 1 is returned.

Since you've created a two-dimensional array, all command that use dimensions > 2 return 1.

Try this and let me know whether you understand the output (don't copy and paste, as that often generates wrong outputs):

A = ones(2, 3, 4);
[sz1 sz2 sz3] = size(A)
[sz1 sz2 sz3 sz4 sz5] = size(A)

Read more here.

Edit: Grammar and formatting.